Java: Explanation of unknown java syntax

Question

Can someone please tell me what this is doing. Its a class that holds an extending generic of itself? what does that even mean?

 public abstract class AbstractStructureBuilder<T extends AbstractStructureBuilder> implements IStructureBuilder
    {

       //abstract and concrete methods in here
    }

possible duplicate of [Why in java enum is declared as Enum>](http://stackoverflow.com/questions/3061759/why-in-java-enum-is-declared-as-enume-extends-enume) in particular [this answer](http://stackoverflow.com/a/3061776/829571). — assylias, Nov 29 '12 at 18:33
@assylias I'm asking a question of unknown syntax, I cannot draw correlation to an unknown topic. — stackoverflow, Nov 29 '12 at 18:34
I commented on your answer. Thanks again for the supporting information — stackoverflow, Nov 29 '12 at 18:42
@stackoverflow Not sure what you mean - I'm just pointing out the fact that a very good answer has been given on a very similar question, which you might find useful. — assylias, Nov 29 '12 at 18:48
@assylias It appeared to me that I asked the question and you indicated it was a duplicate and voted to close the question. If that close vote wasn't yours then I apologize. — stackoverflow, Nov 29 '12 at 18:50

Miltos Kokkonidis · Accepted Answer · 2012-11-29T18:39:32.463

1

The correct answer and some rational is given here: http://www.angelikalanger.com/GenericsFAQ/FAQSections/TypeParameters.html#FAQ106

edited Nov 29 '12 at 18:39

answered Nov 29 '12 at 18:32

Miltos Kokkonidis

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score 1 · Answer 2 · answered Nov 29 '12 at 18:32

1

It means the AbstractStructureBuilder has a type parameter that extends AbstractStructureBuilder.

answered Nov 29 '12 at 18:32

Garrett Hall

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score 0 · Answer 3 · answered Nov 29 '12 at 18:37

There's not much there, but I would guess this could be a class for representing nodes in a tree or graph. The class would have generified getters and setters. For instance a method getChildren might return a list of T. Then one can extend AbstractStructureBuilder to, for example, make nodes in a family tree. If you do that, then the getter will return List<FamilyTreeNode>.

Java: Explanation of unknown java syntax

3 Answers3